Many large vehicles such as agricultural tractors, construction equipment and the like employ one or more ground engaging tracks as a means for moving the vehicle. Vehicles of this type typically use two or more tracks, each track comprising a continuous loop which runs between a forward and rearward sprocket. Because the track provides a large ground engaging surface area, it has many advantages including providing excellent traction and maximum weight distribution. However, track systems are not without their drawbacks. For example, it is well known that for a track system to operate with maximum longevity and minimal maintenance, it must be operated under optimum tension. Excessive tension tends to accelerate the wear of the system components including the track, track sprockets and the like. On the other hand, insufficient tension provides unacceptable levels of play (or slop) between the track and the guide sprockets. If the tension is too low, the track could possibly come off the sprockets.
Because of the above advantages in maintaining the track at its optimum tension, many systems have been developed to adjust track tension. One well known method involves making one of the track sprockets adjustable in a way which enables tension to be applied to the track. In the past, mechanical systems have been used to adjust sprocket position. Such mechanical systems include connecting the axle of a sprocket to a movable housing which is attached to a mechanical extension means such as a jack screw, turn buckle or the like. As the mechanical extension means is manipulated manually, the sprocket can be moved thereby placing more or less tension on the track. Another commonly used method to adjust track tension is to replace the mechanical adjusting means with a grease cylinder. Under this type of system, when it is desired to adjust track tension, grease is pumped into the cylinder which extends a cylinder arm and positions the track sprocket to tighten the track. Under this type system if too much grease is pumped into the grease cylinder, a relief valve is provided for discharging grease from the cylinder. Although these prior art methods are somewhat effective, they suffer from severe drawbacks. For example, both of the above mentioned systems require a high degree of operator involvement. For example, they require the operator to check the tension in the system at a regular interval, and if the tension has deviated outside of the optimal range, the operator must take the necessary action to place the track tension within the optimum range. Under this type of arrangement, the operators are prone to forget to check track tension, or even when they do remember to check track tension, they must keep the proper tools with them to adjust the system should adjustment be required. Additionally, equipment of this nature is often operated in, or under, extremely undesirable conditions such as muddy or wet locations or sights which are exposed to outdoor elements. Under these conditions, it is undesirable to have the operator leave the cab to perform the track tensioning operation.
Thus, it is desirable to provide a track adjustment system which operates automatically without any substantial involvement from the vehicle operator.
Additionally, it is desirable for a track adjustment system to operate at regular intervals so that the track is maintained at optimal tension at all times. It is also desirable to have an automatic track adjustment system which is durable, comprises a minimal amount of components and is easy to service.